RESUMO
The evaluation of the biological and epidemiological properties of Ebola, Marburg, Lassa, and Machupo viruses suggests that they are of social importance for health care authorities. The studies have created prerequisites to the development of reliable biosafety means against these pathogens. Particular emphasis is laid on the methods for infection diagnosis and on the studies to design specific protective agents--immunoglobulins and inactivated vaccines.
Assuntos
Arenavirus do Novo Mundo/patogenicidade , Surtos de Doenças , Ebolavirus/patogenicidade , Febre Hemorrágica Americana , Febres Hemorrágicas Virais , Vírus Lassa/patogenicidade , Marburgvirus/patogenicidade , Animais , Especificidade de Anticorpos/imunologia , Antígenos Virais/administração & dosagem , Antivirais/uso terapêutico , Arenavirus do Novo Mundo/imunologia , Ebolavirus/imunologia , Saúde Global , Febre Hemorrágica Americana/epidemiologia , Febre Hemorrágica Americana/patologia , Febre Hemorrágica Americana/terapia , Febres Hemorrágicas Virais/epidemiologia , Febres Hemorrágicas Virais/patologia , Febres Hemorrágicas Virais/terapia , Cavalos , Humanos , Imunização , Imunoglobulinas/imunologia , Imunoglobulinas/uso terapêutico , Infecção Laboratorial/epidemiologia , Vírus Lassa/imunologia , Marburgvirus/imunologia , Ribavirina/uso terapêutico , Vacinas Virais/administração & dosagem , VirulênciaRESUMO
A replicon vaccine vector system was developed from an attenuated strain of Venezuelan equine encephalitis virus (VEE). The replicon RNA consists of the cis-acting 5' and 3' ends of the VEE genome, the complete nonstructural protein gene region, and the subgenomic 26S promoter. The genes encoding the VEE structural proteins were replaced with the influenza virus hemagglutinin (HA) or the Lassa virus nucleocapsid (N) gene, and upon transfection into eukaryotic cells by electroporation, these replicon RNAs directed the efficient, high-level synthesis of the HA or N proteins. For packaging of replicon RNAs into VEE replicon particles (VRP), the VEE capsid and glycoproteins were supplied in trans by expression from helper RNA(s) coelectroporated with the replicon. A number of different helper constructs, expressing the VEE structural proteins from a single or two separate helper RNAs, were derived from attenuated VEE strains Regeneration of infectious virus was not detected when replicons were packaged using a bipartite helper system encoding the VEE capsid protein and glycoproteins on two separate RNAs. Subcutaneous immunization of BALB/c mice with VRP expressing the influenza HA or Lassa virus N gene (HA-VRP or N-VRP, respectively) induced antibody responses to the expressed protein. After two inoculations of HA-VRP, complete protection against intranasal challenge with influenza was observed. Furthermore, sequential immunization of mice with two inoculations of N-VRP prior to two inoculations of HA-VRP induced an immune response to both HA and N equivalent to immunization with either VRP construct alone. Protection against influenza challenge was unaffected by previous N-VRP immunization. Therefore, the VEE replicon system was characterized by high-level expression of heterologous genes in cultured cells, little or no regeneration of plaque-forming virus particles, the capability for sequential immunization to multiple pathogens in the same host, and induction of protective immunity against a mucosal pathogen.
Assuntos
Proteínas do Capsídeo , Capsídeo/imunologia , Vírus Defeituosos/fisiologia , Vírus da Encefalite Equina Venezuelana/genética , Vetores Genéticos/genética , Vírus Auxiliares/fisiologia , Glicoproteínas de Hemaglutininação de Vírus da Influenza/imunologia , Vírus da Influenza A/imunologia , Vírus Lassa/imunologia , Replicon , Vacinas Combinadas/genética , Vacinas Sintéticas/genética , Vacinas Virais/genética , Animais , Anticorpos Antivirais/biossíntese , Anticorpos Antivirais/imunologia , Especificidade de Anticorpos , Capsídeo/biossíntese , Capsídeo/genética , Linhagem Celular , Embrião de Galinha , Chlorocebus aethiops , Cricetinae , Patos , Vírus da Encefalite Equina Venezuelana/imunologia , Vírus da Encefalite Equina Venezuelana/fisiologia , Fibroblastos , Regulação Viral da Expressão Gênica , Glicoproteínas de Hemaglutininação de Vírus da Influenza/biossíntese , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Vírus da Influenza A/genética , Vírus Lassa/genética , Mesocricetus , Camundongos , Camundongos Endogâmicos BALB C , Infecções por Orthomyxoviridae/prevenção & controle , RNA/genética , RNA Viral/genética , Proteínas Recombinantes de Fusão/biossíntese , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/imunologia , Vacinação , Vacinas Atenuadas/imunologia , Vacinas Combinadas/imunologia , Vacinas Sintéticas/imunologia , Células Vero , Proteínas Estruturais Virais/biossíntese , Proteínas Estruturais Virais/genética , Vacinas Virais/imunologiaRESUMO
Monoclonal antibodies (MAbs) were produced against two African arenaviruses, Lassa virus and Mopeia virus. Competitive binding analysis of MAbs identified four antigenic sites on the nucleoprotein (NP), two on glycoprotein 1 (GP1) and six on glycoprotein 2 (GP2) of the Josiah strain of Lassa virus. 64 virus isolates from western, central and southern Africa were all consistently distinguishable by MAbs to certain epitopic sites on GP1, GP2 and NP viral proteins. Furthermore, MAbs to Lassa virus GP1 and NP uniformly distinguished viruses from the West African countries of Sierra Leone, Liberia and Guinea from those of Nigeria. GP2-directed MAbs to two African arenaviruses reacted broadly with South American arenaviruses demonstrating that an epitopic site on GP2 may be the most highly conserved antigen in the arenavirus group.